Field of the Invention
This invention relates to a dual temperature thermostatic controller for use in a house, apartment, business establishment or other dwelling, as a means of minimizing waste of heating fuel or air conditioner electricity, when the user leaves his home, business establishment, or other dwelling unoccupied for extended periods of time. Typical examples are times when the user is away at work, or shopping, etc., or when the user leaves his business establishment for closing-hours, or other reasons. It will control and maintain a "second", and more economical, preselected room temperature (cooler in winter, or warmer in summer) during the time the user is gone, and will automatically restore the room temperature to a "normal" comfortable level at a pre-set time before the user returns to the dwelling. It also serves as a "comfort" product for users who desire to sleep in a cool room in winter, and would like the room temperature to warm-up at a pre-set time before arising from bed. Maintaining a second temperature operation is also a safety feature to prevent possible household water-line freeze-ups in winter, or excessive interior dwelling heat in summer (as opposed to the risks of simply turning off the heating or air conditioning systems when leaving for extended periods). This feature also provides protection for small children, invalids, pets, and the like, who may be left unattended for long periods of time unintentionally.
Prior Art
A dual temperature thermostat was described in U.S. Pat. No. 1,720,723 and consisted of two separate bi-metallic thermostats in one casing, and clock actuated, for day/night operation, to be used as a primary thermostat in a dwelling. Later patents covered mechanical and electrical variations thereof, including using one bi-metallic or thermal element, with two mechanical stops in place of using dual elements.
This type of device, or variation thereof, usually requires disconnecting and removal of the existing thermostat (physically substituting the new device in its place), and is normally attempted by an experienced heating system installer or electrician. Otherwise, this type of controller is installed as part of an original heating system installation. Either installation is normally not attempted by the average household user who has no prior knowledge of heating or air conditioning systems. Also, apartment renters may be prohibited from making such installation.